The picture that I attached is showing a pump which I am trying to find the flow velocity near blade surfaces. I added a cylindirical area around impeller and applied rotating frame. For the first trial my BC's are
1) Inlet Flow Rate;
2) Outlet Environment Pressure;
3) Real Wall to Impeller;
4) Real Wall as Stator to Water touching faces inside the pump.
As a second study I deleted the rotating frame and applied these boundaries;
1) Inlet Flow Rate;
2) Outlet Environment Pressure;
3) Real Wall as Wall Motion to Impeller's Water touching faces.
Which one do you think is the best and the most logical way to do that kind of study?
Do not use a Real Wall condition on faces as an attempt to simulate motion, this will simply not work. The Real Wall velocity condition is meant to correctly boundary layer conditions for simulating a body in motion. For example, if you were simulating a car moving at velocity you may choose to model the ground and give it a Real Wall velocity condition matching the bulk average fluid flow, in order so that the model does not apply a non-slip boundary condition with zero velocity on the ground.
For your calculation stick with a local rotating region and make sure that it covers every part of the rotor geometry.